(ChemotherapyAdvisor) – Why is 45 years of age used as the prognostic cut-off in staging papillary thyroid cancer? In answering that question, investigators determined those 45 to <65 years of age have similar outcomes to younger patients, suggesting this may be a more accurate age marker for prognosis, according to a presentation at the 82nd Annual Meeting of the American Thyroid Association (ATA) in Québec City, Québec, Canada, on September 21.
A review of the literature found that the age of 45 years—used to establish staging in well-differentiated papillary thyroid cancer using the American Joint Committee on Cancer and the International Union Against Cancer TNM Classification of Malignant Tumors (TNM) staging system—dates to a 1979 article by Byar et al in the European Journal of Cancer. “This study was underpowered and not specific to well-differentiated thyroid cancer,” noted Lindsay Bischoff, MD, of the Thomas Jefferson University Hospital in Philadelphia, PA.
“Our empiric clinical observation has been that patients aged 45 to 64 years appear to have similar long-term outcomes when compared to patients <45 years of age. We thus questioned the origin and accuracy of age 45 as the prognostic cut-off,” the investigators reported.
Using the Surveillance Epidemiology and End Results (SEER) database and ICD-O codes specific to papillary thyroid cancer, they identified 53,581 patients with all stages of histologically confirmed disease. Data were stratified in 5-year categories by age at diagnosis from 20 to 84 years of age; those 85 years and older were categorized together.
“Overall 5-year survival remained above 90% for all age groups under 65 years,” Dr. Bischoff noted. “Patients 65 years and above had a progressively less favorable prognosis with each advancing age group.”
While age at diagnosis appears to play a role in papillary thyroid cancer outcomes, a more appropriate age marker prognosis may be >65 years, as it defines a cohort destined to have <90% 5-year survival.
“Use of this older age marker would result in downstaging of many patients and may be a more accurate reflection of the favorable prognosis of papillary thyroid cancer, avoiding potentially additional unnecessary ancillary therapies and allaying patients’ fears about the longevity with this condition,” she concluded.
Abstract [Click Full Text PDF and search using author name Bischoff]